360 SECTIONAL TRANSACTIONS.— G. 



Prof. Sir Leonard Hill, F.R.S. — By the use of a submersible decompression 

 chamber, designed by Mr. R. H. Davis, combined with the breathing of oxygen 

 during decompression, the limit of depth for diving has been greatly extended. It 

 has been shown that it is safe to breathe oxygen at an absolute pressure of three 

 atmospheres for half an hour. Baboons, goats, and a donkey have been compressed 

 to 300 feet of water pressure, and in some cases to 350 and 400 feet. They behave 

 normally while under such pressures and can be decompressed safely with the help 

 of oxygen in from half an hour to forty-five minutes. Divers have been exposed 

 safely to 300 feet of water pressure, and proved as capable of doing work at that 

 pressure as at less pressures. It is safe to decompress rapidly from 300 or 400 feet 

 to 66 feet of water pressure because bubbles of nitrogen are prevented from forming 

 by the latter pressure. At 66 feet and downwards during decompression oxygen is 

 breathed ; by filling the lungs with oxygen the diffusion of nitrogen from the blood is 

 hastened. The decompression is made in stages, there being a pause at 30, 15, 10 and 

 5 lb. of pressure. Any sign of ' bends ' coming on at a lower pressure stage is removed 

 by returning to the one higher and breathing oxygen for a longer period. Trials 

 are being made on animals of more prolonged exposures, using partly deoxygenated air 

 for the higher pressures so as to avoid any danger of oxygen poisoning. The depth 

 possible for submarine work in compressed air no doubt can be greatly extended 

 by the use of oxygen breathing apparatus in the decompression air lock. 



The experiments are being carried out with pressure chambers set up by Mr. R. H. 

 Davis at Messrs. Siebe, Gorman's works, and with his co-operation.' Deep-sea 

 divirig-tests are being carried out by the Admiralty Diving Committee and will be 

 published in due course. 



The katathermometer has proved of considerable value as a measure of ventilation 

 and as a sitnple anenometer. Calibrated from 100 ° to 95° F., it enables one to measure 

 the rate of cooling on its surface at approximately skin temperature. A new form 

 has been introduced calibrated from 130° to 125° F., for use in hot climates and work- 

 shops. A nomogram has been prepared from the results of extensive observations 

 in wind tunnels at various known temperatures and wind velocities, and by means of 

 this the velocity of air movement can be at once arrived at after making readings of 

 the instrument. The instrument, and nomogram, which answers both for the old and 

 new form, can be had from Messrs. Hicks, 8 Hatton Garden, E.C. Messrs. Angus 

 and Soper have carried out the preparation of the nomogram. 



Capt. G. C. C. Damant, C.B.E., R.N.— Theory of Haldane's method of decom- 

 pression and the experiments which led to the framing of the Admiralty tables for 

 controlling the ascent of divers so as to protect them from compressed air illness. 

 Twenty years' experience of this method in practical diving work in deep water— the 

 lessons learned and their possible application to caisson work. 



Afternoon. 

 Visit to Bristol Aeroplane Company, Filton. 



Visit to Messrs. Stothert & Pitt's Works, Bath. 



Saturday, September 6. 



Excursion to G.W.R. Locomotive Works, Swindon. 



Monday, September 8. 



The Trend op Airship Construction : — 



Lieut.-Col. V. C. Richmond, O.B.E.— T/je Development of Rigid Airship 

 Construction. 



(1 ) The Influence of Operational Conditions on Design. 



(2) S}Mpe and Aerodynamic Characteristics.— The influence of fineness ratio, and 

 block coefficient on drag. The effect of turbulence on a parasitic resistance, etc. 



